/*
 * [New BSD License]
 * Copyright (c) 2011-2012, Brackit Project Team <info@brackit.org>  
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the Brackit Project Team nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.brackit.xquery.expr;

import org.brackit.xquery.QueryContext;
import org.brackit.xquery.QueryException;
import org.brackit.xquery.Tuple;
import org.brackit.xquery.atomic.Str;
import org.brackit.xquery.atomic.Una;
import org.brackit.xquery.xdm.Expr;
import org.brackit.xquery.xdm.Item;
import org.brackit.xquery.xdm.Iter;
import org.brackit.xquery.xdm.Kind;
import org.brackit.xquery.xdm.Node;
import org.brackit.xquery.xdm.Sequence;

/**
 * 
 * @author Sebastian Baechle
 * 
 */
public class TextExpr extends ConstructedNodeBuilder implements Expr {
	protected final Expr expr;

	protected final boolean appendOnly;

	public TextExpr(Expr expr, boolean appendOnly) {
		this.expr = expr;
		this.appendOnly = appendOnly;
	}

	@Override
	public final Sequence evaluate(QueryContext ctx, Tuple tuple)
			throws QueryException {
		return evaluateToItem(ctx, tuple);
	}

	@Override
	public Item evaluateToItem(QueryContext ctx, Tuple tuple)
			throws QueryException {
		// See XQuery 3.7.3.4 Computed Text Constructors
		Sequence sequence = expr.evaluate(ctx, tuple);
		StringBuilder buf = new StringBuilder("");

		if (sequence != null) {
			if (sequence instanceof Item) {
				String s = ((Item) sequence).atomize().stringValue();
				buf.append(s);
			} else {
				boolean first = true;
				Iter it = sequence.iterate();
				try {
					Item item;
					while ((item = it.next()) != null) {
						String s = item.atomize().stringValue();
						if (!s.isEmpty()) {
							if (!first) {
								buf.append(' ');
							}
							first = false;
							buf.append(s);
						}
					}
				} finally {
					it.close();
				}
			}
		}

		String content = buf.toString();

		if (appendOnly) {
			((Node<?>) tuple.get(tuple.getSize() - 1)).append(Kind.TEXT, null,
					new Str(content));
			return null;
		}

		Node<?> node = ctx.getNodeFactory().text(new Una(content));
		return node;
	}

	@Override
	public boolean isUpdating() {
		return expr.isUpdating();
	}

	@Override
	public boolean isVacuous() {
		return false;
	}
}
